2024-03-28T19:18:55Zhttp://digital.csic.es/dspace-oai/requestoai:digital.csic.es:10261/204402021-10-11T11:13:59Zcom_10261_97com_10261_4col_10261_350
http://hdl.handle.net/10261/20440
10.1088/0004-637X/696/2/1142
20373
Spectral evolution of superluminal components in parsec-scale jets
American Astronomical Society
2009
artículo
Mimica, Petar
Aloy, Miguel Ángel
Agudo, Iván
rp07533
Martí, José M.
Gómez Fernández, J. L.
rp07536
Miralles, Juan Antonio
Galaxies: jets
Hydrodynamics
Radiation mechanisms: non-thermal
Relativity
2009-04
27 pages, 18 figures, 1 table, 1 appendix.-- Pre-print archive.
We present numerical simulations of the spectral evolution and emission of radio components in relativistic jets. We have developed an algorithm (SPEV) for the transport of a population of non-thermal electrons including radiative losses. For large values of the ratio of gas pressure to magnetic field energy density, \ab \sim 6\times 10^4, quiescent jet models show substantial spectral evolution, with observational consequences only above radio frequencies. Larger values of the magnetic field (\ab \sim 6\times 10^2), such that synchrotron losses are moderately important at radio frequencies, present a larger ratio of shocked-to-unshocked regions brightness than the models without radiative losses, despite the fact that they correspond to the same underlying hydrodynamic structure. We also show that jets with a positive photon spectral index result if the lower limit \gamma_min of the non-thermal particle energy distribution is large enough. A temporary increase of the Lorentz factor at the jet inlet produces a traveling perturbation that appears in the synthetic maps as a superluminal component. We show that trailing components can be originated not only in pressure matched jets, but also in over-pressured ones, where the existence of recollimation shocks does not allow for a direct identification of such features as Kelvin-Helmholtz modes, and its observational imprint depends on the observing frequency. If the magnetic field is large (\ab \sim 6\times 10^2), the spectral index in the rarefaction trailing the traveling perturbation does not change much with respect to the same model without any hydrodynamic perturbation. If the synchrotron losses are considered the spectral index displays a smaller value than in the corresponding region of the quiescent jet model.
openAccess
Astrophysical Journal
2009
696
1142
1163